The increasing importance of power quality and reliability has produced an increasing need for electrical utilities to monitor their infrastructure with test equipment. In addition, end users who are interested in controlling energy consumption and improving efficiency also have a need to monitor their systems with electrical test equipment. Although the recommended practice in the past has been to disconnect all live voltage before connecting monitoring equipment, the trend today is towards maximum reliability and minimum outage time. For at least this reasons, it is desirable for the installer to connect any measurement equipment to voltage and current monitoring points with full voltage and current, to avoid interrupting power delivery.
Connecting electrical monitoring equipment to live voltage is hazardous, and adherence to multiple sets of safety regulations, including the NEC, OSHA, NFPA, and/or any other suitable safety regulations, is desirable. In particular, arc-flash equipment, including flame retardant clothing, full helmet, and insulating gloves, is useful for gaining access to many areas. Operating electronic equipment while wearing full protective clothing is very difficult due to limited visibility and manual dexterity.
In addition, connecting electrical monitoring equipment is very error-prone. Each voltage phase must be matched with the appropriate voltage input on the monitor, and each current channel to the corresponding current input. Further, the polarity of both the voltage and current inputs is also important for power and phase angle measurements. It can be difficult to determine the correct phase and polarity relationships by sight at many electrical monitoring points. Another complication is that specialized monitoring equipment is often only used infrequently, resulting in users who are unfamiliar with the correct instrument hookup.
For at least these reasons, it is desirable for the user to carefully read all hookup instructions for the instrument, pay attention to probe channel number and phasing, and correctly identify all monitoring points.